Home Assistant Energy Monitoring: The Complete Guide

You can't optimize what you can't measure. That's the fundamental truth of home energy management. Before you build automations, before you optimize tariffs, before you do anything smart with energy—you need to know where your watts are going.

This guide covers everything you need to monitor energy consumption in Home Assistant: from choosing the right hardware to configuring sensors and building a monitoring system that actually tells you something useful.

The Two Levels of Energy Monitoring

There are two approaches, and you probably want both:

• Whole-home monitoring: One device at your electrical panel that tracks total consumption and (if applicable) solar production. This is the foundation.
• Per-device monitoring: Smart plugs or circuit-level monitors on individual appliances. This answers "which device is eating my energy?"

Start with whole-home monitoring. Add per-device tracking as you identify the biggest consumers.

Whole-Home Monitoring Options

P1 Smart Meter (Europe)

If you're in the Netherlands, Belgium, or another European country with DSMR-compatible smart meters, this is the easiest path. A P1 dongle plugs into the diagnostic port on your meter and sends data directly to Home Assistant.

• Hardware: SlimmeLezer+, HomeWizard P1, or similar (~€30-40)
• Data: Real-time power (W), total energy (kWh), gas consumption, voltage
• Update rate: Every 1-10 seconds depending on meter type
• Integration: Auto-discovered by Home Assistant, native integration

CT Clamp Monitors (Universal)

Current transformer clamps wrap around the main cables in your electrical panel. No electrician needed—they clip on without touching any wires.

• Shelly Pro 3EM: 3-phase monitoring, Wi-Fi, ~€80. Excellent Home Assistant integration.
• Emporia Vue: Up to 16 circuits, ~€100-150. Good for per-circuit breakdown.
• Shelly EM: Single or dual channel, ~€30-40. Budget option for basic monitoring.

Smart Meter Integration (US)

In the US, many utilities provide smart meter data through third-party services:

• Emporia Vue Utility Connect: Reads your existing meter's data via the utility API
• Sense Energy Monitor: CT clamp device with AI-based appliance detection (~$300)
• Rainforest Eagle: Connects to Zigbee-equipped smart meters

Per-Device Monitoring

Once you know your total consumption, the next question is always: "What's using all this energy?" Smart plugs with energy monitoring solve this.

Recommended Smart Plugs

• Shelly Plug S (EU) / Shelly Plug US: Wi-Fi, local API, excellent HA integration. ~€20. Best all-round choice.
• Nous A1T (Tasmota): Pre-flashed with Tasmota for full local control. ~€12. Budget pick.
• Eve Energy (Matter): Works over Thread/Matter. €40. Premium option with no cloud dependency.

What to Monitor First

Don't put smart plugs on everything. Start with these high-impact devices:

1. Refrigerator/freezer: Runs 24/7, easy to overlook. A failing fridge can use 3x normal energy.
2. Washing machine & dryer: High consumption, easy to schedule during cheap hours.
3. Home office equipment: Monitor, PC, and peripherals often draw 200-500W in standby.
4. Entertainment center: TV, soundbar, game console. 20-50W standby is common.

Configuring Sensors in Home Assistant

Most energy monitoring devices create sensors automatically when you add the integration. But you'll want to verify they're configured correctly for the energy dashboard.

Essential Sensor Attributes

Every energy sensor needs these attributes to work with the energy dashboard:

device_class: energy
state_class: total_increasing
unit_of_measurement: kWh

For power sensors (real-time wattage), the attributes should be:

device_class: power
state_class: measurement
unit_of_measurement: W

Creating Utility Meter Sensors

Utility meters reset at intervals (daily, monthly) and are essential for tracking consumption over time:

utility_meter:
  daily_energy:
    source: sensor.total_energy
    cycle: daily
  monthly_energy:
    source: sensor.total_energy
    cycle: monthly

These utility meter sensors give you clean daily and monthly totals that are perfect for tracking trends and comparing periods.

Building Your Monitoring Stack

Here's the recommended progression for building a complete energy monitoring setup:

Phase 1: Whole-Home (Week 1)

• Install a P1 dongle or CT clamp monitor
• Add it to Home Assistant
• Configure the energy dashboard
• Set up daily and monthly utility meters

Phase 2: High-Impact Devices (Week 2-3)

• Add smart plugs to your top 4-5 consumers
• Add them as individual devices in the energy dashboard
• Let it collect data for at least a week

Phase 3: Analysis & Action (Week 4+)

• Review the data: which devices consume the most?
• Look for standby consumption that can be eliminated
• Identify appliances that can be shifted to cheap hours
• Build automations based on real data

Cost Tracking

Energy data without cost data is only half the picture. Once your monitoring is running, add cost sensors to translate kWh into euros:

template:
  - sensor:
      - name: "Today Energy Cost"
        unit_of_measurement: "€"
        device_class: monetary
        state: >
          {{ (states('sensor.daily_energy') | float(0)
              * states('sensor.electricity_price') | float(0.25))
             | round(2) }}

For dynamic pricing, use integrations like Nordpool, ENTSO-e, or Tibber that provide real-time price sensors. These work directly with the energy dashboard's built-in cost tracking.

What Good Monitoring Looks Like

After a month of monitoring, you should be able to answer these questions at a glance:

• What's my average daily consumption?
• Which 3 devices use the most energy?
• How much does standby power cost me per month?
• What time of day is my consumption highest?
• How does this month compare to last month?

If you can answer those five questions, your monitoring setup is doing its job. Everything else—automations, optimizations, peak shaving—builds on that foundation.

Start measuring. Start saving.